15-2 Riverstone Networks RS Switch Router User Guide Release 8.0
Enabling IS-IS on the RS IS-IS Configuration Guide
To enable IS-IS on an interface, enter the following command in Configure mode:
15.3 ENABLING IS-IS ON THE RS
IS-IS is disabled on the RS by default. To enable IS-IS on the RS, enter the following command in Configure mode:
15.4 SETTING IS-IS GLOBAL PARAMETERS
The RS provides global IS-IS parameters which control the router’s operating level, timers, authentication, and other
IS-IS functions. The following sections discuss the global IS-IS parameters that you can modify to better suit your
routing environment.

15.4.1 Setting the IS Operating Level

An IS can be configured to route Level 1 and/or Level 2 traffic. Level 1 routing handles all intra-domain traffic, (all
traffic within an IS-IS area). Level 2 routing handles all inter-domain traffic (all traffic between different IS-IS areas).
On the RS, you can set the operating level for the router and on a per-interface basis. The default level for both the
router and its interfaces is Level 1- and-2. You may change the default for either or both. If you do so, keep in mind
that the operating level of the interfaces must agree with the operating level of the RS. Therefore if a router’s operating
level is set to Level 1 or to Level 2, its interfaces should be set to the same level. But if the interfaces will be routing
both Level 1 and Level 2 traffic, then you should set the router’s level to Level 1-and-2.
To set the router’s operating level, enter the following command in Configure mode:

15.4.2 Setting the PSN Interval

On point-to-point subnetworks, an IS sends a Partial Sequence Number PDU (PSNP) to acknowledge each LSP it
receives. PSNPs contain the following information: LSP ID, the LSP’s sequence number, the LSP’s Checksum and
the LSP’s Remaining Lifetime.
Creates an IS-IS interface on a router. isis add interface <string>|all
Enables IS-IS on the router. isis start
Sets the IS-IS level for a router. isis set level 1|2|1-and-2